Electrochemical performance of multiphase nickel hydroxide

摘要

The high density nano-crystalline multiphase nickel hydroxide containing at least three doping elements was synthesized and its electrochemical characteristics were studied. The electrochemical behavior of the high density spherical multiphases α-Ni(OH)_2 were also investigated. The results show that the structure of the material is a mixed phase of α-Ni(OH)_2 and β-Ni(OH)_2, which has a the same stabilized structure as α -Ni(OH)_2 during long-term charge/discharge process. High density spherical multiphases α -Ni(OH)_2 have a much better redox reversibility, a much lower oxidation potential of Ni( Ⅱ) than the corresponding oxidation state in the case of β-Ni(OH)_2, and a much higher reduction potential. They exchange one electron during electrochemical reaction and have a higher proton diffusion coefficient. The mechanism of the electrode reaction is proton diffusion, and the proton diffusion coefficient is 5.67x 10~(-10) cm~2/s. Moreover, they reveal a higher discharge capacity than β-Ni(OH)_2/ β-NiOOH because they exchange one electron per nickel atom during charge/discharge process.